Half-space carriage return mechanism for typewriters

ABSTRACT

A half-space carriage return mechanism for typewriters, having a rack secured to the carriage and normally engaged by an escapement dog adapted to be disengaged momentarily from the rack to letter space the carriage, comprises a pawl movable in a first direction to engage the rack and to return the carriage half a space, and means actuatable for momentarily disengaging the pawl from the rack simultaneously with disengagement of the escapement dog when and only when the pawl is in the position in which it has backspaced the carriage through half a space, to cause said carriage to be advanced offset half a space with respect to normal letter spaced positions.

United States Patent 2,212,692 8/1940 Kitchens 605,201 6/1898 LattaInventors Appl. No. Filed Patented Assignee Priority HALF-SPACE CARRIAGERETURN MECHANISM ITOR TYPEWRITERS 4 Claims, 3 Drawing Figs.

197/82, 197/ 84R Int. Cl B4lj 19/62 Field of Search 197/84,

References Cited UNITED STATES PATENTS Primary Examiner-Emest T. Wright,Jr. Attorney-Kevin C. McMahon ABSTRACT: A half-space carriage returnmechanism for typewriters, having a rack secured to the carriage andnormally engaged by an escapement dog adapted to be disengagedmomentarily from the rack to letter space the carriage, comprises a pawlmovable in a first direction to engage the rack and to return thecarriage half a space, and means actuatable for momentarily disengagingthe pawl from the rack simultaneously with disengagement of theescapement dog when and only when the pawl is in the position in whichit has backspaced the carriage through half a space, to cause saidcarriage to be advanced offset half a space with respect to normalletter spaced positions.

PATENIEU MAY] 1 1971 SHEET 1 BF 2 INVENTORS VENANZIO wcnzmn CREMASCODOMENICO ROANO BY 7% PATENIED am 1 I97! 3578.132

sum 2 or 2 ENTOR;

VENAN MICH TT' RE I OME NO HALF-SPACE CARRIAGE RETURN MECHANISM FORTYPEWRITERS BACKGROUND OF THE INVENTION The present invention relates toa half-space carriage return mechanism for typewriters, having a toothedspacing member connected to the carriage and normally engaged by anescapement dog.

Various half-space return mechanisms of this kind are known. In general,with these mechanisms when it is desired to insert an omitted letter ina word, it is necessary to depress the backspace key as each typing keyis depressed. Following the striking of each type, the backspace keymust also be released. The combined action of the release of thebackspace key and the operation of the escapement mechanism causes thecarriage to advance; one space and a half instead of one space. Therehas already been proposed an arrangement for returning the carriage halfa space, in which the escapement dog is mounted on a support which isdisplaced on the depression of the half-space return key, whereby theescapement tooth can.

thereafter be actuated while the half-space return key is keptdepressed. Due to the dual function of the escapement dog, however, thisarrangement is subject to trouble with the escapement and carriagerebound.

SUMMARY OF THE INVENTION tions, a pawl, a support pivotally mountingsaid pawl, a

depressible half-space carriage return key, means operable at thedepression of said key for moving said support to displace said pawl soas to engage said spacing member and to return said carriage half aspace, said operable means keeping said support so moved as long as saidkey remains depressed, means associated with said pawl and actuatablesimultaneously with said spacing control means, and an element on saidpawl normally ineffective for being operated by said associated means,said element upon so displacing said pawl becoming effective, saidassociated means when operating said element causing said pawl to turnon said support for tem-- porarily disengaging said spacing member thuscausing said carriage to be advanced stepwise offset half a space withrespect to said letter spaced positions.

An embodiment of the invention will now be described by way of examplewith reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial plan view of anelectric typewriter incorporating a half-space return mechanismaccording to the invention,

FIG. 2 is a partial section taken on the line 11-11 of FIG. 1, and

FIG. 3 is a section taken on the line III-Ill of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring moreparticularly to FIG. 2, the reference 5 indicates generally the usualpaper carriage of an electric typewriter, which is slidable transverselyon a guide 6 fixed to the frame of the machine and is pulled towards theleft (FIG. 1) by the conventional carriage draw spring indicatedgenerally by the reference 7. Moreover, there is fixed to the carriage 5a toothed spacing member formed by a rack 8 normally engaged by amovable escapement dog 9.

The escapement dog 9 is pivotally mounted on a pin 10 carried by a lever11 and is held in engagement with the rack 8 by a spring 12. The lever11 is pivotally mounted on a fixed pin 13 and is urged in a clockwisedirection by a spring 14, the action of which predominates over that ofthe spring 12. As the action of the carriage draw spring 7 predominatesover that of the spring 14, however, the rack 8 normally keeps the lever11 bearing against a fixed stop 15. One end 16 of the lever 11 isnormally engaged by a lug 17 of a hook 18 pivotally mounted on a fixedpin 19 and urged in a clockwise direction by a spring 20.

The escapement dog 9 is actuated to cause the carriage 5 to advancestepwise by means of a cam 21 (FIG. 2) which, on the depression of eachtyping key, is rotated through a cycle of in a known manner by a drivingshaft 22 rotating continuously. Bearing normally against the cam 21through the action of a spring 23 is a roller 24 on a lever 25 pivotallymounted on a fixed spindle 26. The lever 26 cooperates with a bent lug75 of an escapement control lever 27 fixed on a shaft 28 rotatable onthe machine frame. The lever 27 is provided with a projection 29 adaptedto cooperate both with a projection 30 of the hook 18 (FIG. 1) and withone end 31 of a lever 32 having a slot 33 in engagement with a fixed pin34. The lever 32 is normally kept bearing against the fixed stop 15 by aspring 35 and is provided with :1 lug 36 adapted to cooperate with ashoulder 37 of the escapement dog 9.

At each typing cycle, the cam 21 (FIG. 2) causes the lever 25 to rotatein an anticlockwise direction, whereby the control lever 27 is rotatedin a clockwise direction. The projection 29 of the control lever 27first engages the end 31 (FIG. I) of the lever 32, which is rotated inan anticlockwise direction. The lug 36 of the lever 32 then acts on theshoulder 37 of the escapement dog 9, which is disengaged from the rack8. Immediately afterwards, the projection 29 engages the projection 30of the hook 18, which releases the lever 11. By the effect of the spring14, the liner 11 is now rotated in a clockwise direction until it isarrested against a fixed stop 38.

As the lever 11 rotates, it causes the escapement dog 9 to move towardsthe right and perform a retrograde stroke. The shoulder 37 of theescapement dog 9 now leaves the lug 36, whereby the spring 12 causes theescapement dog 9 to reengage the following tooth of the rack 8independently of the action of the cam 21. Due to the action of thespring 7, the rack 8 now carries the dog 9 along towards the left,bringing the lever 11 back so that it bears against the fixed stop 15.If, after the reengagement of the escapement dog 9 with the rack 8, thelever 32 is still-held rotated, the lug 36 be to the left of theshoulder 37 when the carriage 5 moves to the left. The slot 33 thenallows the lever 32 a certain movement along the pin 34. When thecontrol lever 27 returns to the inoperative position, it permits thehook 18 to reengage the lever 11 and the lever 32 to return in any caseto the position shown in FIG. 1.

The shoulder 37 (FIG. 1) allows the dog 9 to reengage the rack 8 in anycase irrespective of the speed and the profile of the cam 21. Theretrograde stroke of the dog 9 towards the right allows it to reengageunder any circumstance with the rack 8 at the following gap. In fact,even though the profile of the cam 21 is such as normally to permit thespring 7 to shift the carriage 5 slightly to the left from standstillbefore the reengagement of the dog 9, when typing is done at speed thecarriage 5 could be in a state of rebound at the instant ofdisengagement of the dog 9, whereby it would be shifted with some delayin respect to the case when the dog 9 is disengaged while the carriage 5is at a standstill. The dog 9 would then be able to reengage the samegap in the rack 8, which would then be unable to effect the step ofadvance.

The typewriter is equipped with a mechanism for returning the carriage 5half a space, said mechanism comprising a pawl 41 adapted to cooperatewith the rack 8. The pawl 41 is fulcrumed on a pin 42 fixed on a supportformed of a lever 43 fulcrumed on a fixed pin 44. Means for moving thelever 43 are provided, said means comprising a connecting rod 45connected by a pin 39 and a slot 40 to the pawl 41. The connecting rod45 is fulcrumed on a pin 46 of a lever 47 and is provided with a slot 48engaging the pin 42. The connecting rod 45 is moreover equipped with astud 49 normally bearing through the action of a spring 50 against aprojection 51 of the lever 43. Finally, the pawl 41 is provided with anelement or projection 52 adapted to cooperate with a pawl-tuming memberformed of an arm 53 fixed on the shaft 28, when the pawl 41 is moved tothe right with respect to the position of FIG. 1.

The lever 47 is pivotally mounted on a fixed pin 54 and is provided withan aperture 55 in which there is engaged one end of a lever 56 pivotallymounted on a fixed spindle 74 (FIG. 3). The lever 56 is equipped with aroller 57 normally bearing through the action of a spring 58 against acam rotatable on the shaft 22. As the spring 58 prevails over the spring50, it keeps the mechanism inoperative, as shown in FIG. 1. The cam 59is arranged to be picked up for rotation with the shaft 22 by means of aclutch comprising a toothed wheel 60 fixed on the shaft 22 and a clutchpawl 61 pivotally mounted on the cam 59 at 62 and connected at 63 to aring 64. The ring 64 in turn is connected to the cam 59 by means of twosmall levers 65 and a spring 66.

Normally, the ring 64 is arrested by engagement of a lug 67 thereonagainst a lug 68 of a lever 69 pivotally mounted at 70 and carrying theusual half-space return key 71. The lug 68 can moreover cooperate with asecond lug 72 on the ring 64, which second lug 72 is about 180 from thelug 67 with respect to the shaft 22, but at a greater distance from thelatter. The

key 71 can be depressed until it abuts against a fixed pin 73.

The half-space return mechanism operates in the following manner.

By depressing the key 71, the lug 68 of the lever 69 is brought clear ofthe lug 67 of the ring 64, but into the path of the lug 72. The spring66 then causes the ring 64 to rotate in an anticlockwise direction (FIG.3) with respect to the cam 59, causing the pawl 61 to engage with thewheel 60. Driven through the pawl 61, the wheel 60 now carries the cam59 along in an anticlockwise direction from the inoperative positionshown in FIG. 3 to an operative position in which the lug 72 is arrestedagainst the lug 68 of the lever 69.

During this rotation, the cam 59 allows the spring 58 to rotate thelever 56 in an anticlockwise direction through a first stroke thusrocking the lever 47 (P10. 1) in a clockwise direction and moving theconnecting rod 45 towards the right a predetermined stroke. Theconnecting rod 45 then rocks the lever 43 on the pin 44, whereby thepawl 41 is first with the rack 8, as shown in chain-dotted lines in FIG.1, and then pushes the rack 8 together with the carriage backwards halfa space against the action of the spring 7.

1f the key 71 is now released (FIG. 3), the lug 68 frees the lug 72 andis brought back into the path of the lug 67 of the ring 64. The coupling60, 61 is reengaged and causes the cam 59 to rotate through another 180in an anticlockwise direction, as a result of which the carriage 5returns to the original position.

If, on the contrary, the key 71 is kept depressed, the pawl 41 (FIG. 1)holds the carriage 5 shifted to the right half a space. if, keeping thekey 71 depressed, a typing key is now depressed, when the lever 25 (P16.2), rocks the arm 27 to disengage the escapement dog 9, the lever 53(FIG. 3) rotates bodily with the arm 27 and the shaft 28 and temporarilydisengages the pawl 41 from the rack 8.

The pawl 41 remains disengaged from the rack 8 for the time determinedby the profile of the cam 21. This time is normally sufficient for thespring 7, causing the carriage 5 to start from standstill, to move thecarriage 5 to the left by an amount such as to allow the pawl 41 toreengage the following tooth of the rack 8. The dog 9, on the otherhand, reengages the following tooth of the rack 8 independently of thecam 21, as has been seen before. The carriage 5 can now advance onespace to the left with respect to the initial position, being arrestedagain against the pawl 41. It is thus possible to effect the insertionof a character or symbol erroneously omitted by actuating the typingkeys while the key 71 is kept depressed.

Since the typing speed which can be obtained in the case where theoperator keeps the half-space return key 71 depressed is lower than thenormal speed, the initially standing state of the carriage 5 at the timewhen the pawl 41 is disengaged is normally observed. If, by accident,the pawl 41 is not engaged with the rack 8, for example owing to thestopping of the shaft 22 before the end of the cycle of the cam 21, therack 8 is stopped in any case by the escapement dog 9, whereby nodisadvantage occurs.

it is therefore clear that the lever 27 and arm 53 fixed on the shaft 28are able to disengage the pawl 41 shifted to the right temporarily fromthe rack 8 simultaneously with the escapement dog 9, to advance thecarriage 5 one space out of phase by half a space with respect to theadvance controlled by the dog 9.

It is understood that various modifications, improvements and additionsof parts may be made in and to the half-space return arrangementhereinbefore described without departing from the scope of the inventionas defined by the appended claims.

We claim:

1. In a typewriter having a transversely movable carriage, a toothedspacing member connected to said carriage, an escapement dog normallyengaging said spacing member, and

. spacing control means actuatable to disengage said escapement dogtemporarily from said spacing member to cause said carriage to advancestepwise to letter spaced positions, a halfspace carriage returnmechanism comprising in combination:

a. a pawl,

b. a support pivotally mounting said pawl,

c. a depressible half-space carriage return key,

d. means operable at the depression of said key for moving said supportto displace said pawl so as to engage said spacing member and to returnsaid carriage half a space, said operable means keeping said support somoved as long as said key remains depressed,

e. means associated with said pawl and actuatable simultaneously withsaid spacing control means, and

f. an element on said pawl normally ineffective for being operated bysaid associated means, said element becoming effective when saidoperable means so displace said pawl, said associated means whenoperating said element causing said pawl to turn on said support fortemporarily disengaging it from said spacing member simultaneously withdisengagement of said escapement dog for causing said carriage to beadvanced under the control of said pawl stepwise offset half a spacewith respect to said letter spaced positions.

2. A mechanism according to claim 1, wherein said toothed spacing memberis formed of a rack secured to said carriage, comprising in combination:

g. a pawl-turning member included in said associated means andactuatable to engage said element, said element being normally out ofthe path of said pawl-tuming member and being brought on said path uponthe displacement of said pawl by said operable means,

h. an escapement control member included in said spacing control meansfor causing disengagement of said escapement dog from said rack, and,

i. a connecting member for directly interconnecting said escapementcontrol member and said pawl-turning member as to be secured to eachother.

3. A mechanism according to claim 2, comprising in combination:

j. a first cam included in said operable means and power driven from aninoperative position to an operative position to so move said support ondepression of said key and power driven from said operative position tosaid inoperative position on release of said key to cause said supportto be restored, and

k. a second cam included in said spacing control means and poweroperated cyclically to actuate said pawl-turning and escapement controlmembers in such a manner that said escapement dog when disengaged inthis way performs a retrograde stroke and reengages said rack after saidretrograde stroke independently of said first cam.

4. A half-spaced carriage return mechanism for a typewriter having aletter space carriage advance mechanism which includes an escapement dogengageable with a toothed spacing member connected to the carriage forholding the carriage against the action of the carriage advance biasingmeans, and means for disengaging the dog for allowing the carriage toadvance under bias and for reengaging said dog with said spacing memberfor stopping said carriage after it has advanced one character space,comprising: I I

a pawl, normally uncoupled from said spacing member,

a depressible half-space carriage return key,

means operated by the depression of said key for displacing said pawlfor engaging said pawl with said spacing member to return said carriageby one-half character space, said engaging means holding said pawl inits displaced position as long as said key is depressed, means coupledto and operable substantially simultaneously with said escapement dogdisengaging means for disengaging said pawl, only when said pawl is inits displaced position, from said spacing member substantiallysimultaneously with the disengaging of said dog, and

means for recoupling said pawl with said spacing member to stop saidspacing member after it has advanced under the influence of said biasingmeans a distance of onecharacter space from said half character spacereturned position.

1. In a typewriter having a transversely movable carriage, a toothedspacing member connected to said carriage, an escapement dog normallyengaging said spacing member, and spacing control means actuatable todisengage said escapement dog temporarily from said spacing member tocause said carriage to advance stepwise to letter spaced positions, ahalf-space carriage return mechanism comprising in combination: a. apawl, b. a support pivotally mounting said pawl, c. a depressiblehalf-space carriage return key, d. means operable at the depression ofsaid key for moving said support to displace said pawl so as to engagesaid spacing member and to return said carriage half a space, saidoperable means keeping said support so moved as long as said key remainsdepressed, e. means associated with said pawl and actuatablesimultaneously with said spacing control means, and f. an element onsaid pawl normally ineffective for being operated by said associatedmeans, said element becoming effective when said operable means sodisplace said pawl, said associated means when operating said elementcausing said pawl tO turn on said support for temporarily disengaging itfrom said spacing member simultaneously with disengagement of saidescapement dog for causing said carriage to be advanced under thecontrol of said pawl stepwise offset half a space with respect to saidletter spaced positions.
 2. A mechanism according to claim 1, whereinsaid toothed spacing member is formed of a rack secured to saidcarriage, comprising in combination: g. a pawl-turning member includedin said associated means and actuatable to engage said element, saidelement being normally out of the path of said pawl-turning member andbeing brought on said path upon the displacement of said pawl by saidoperable means, h. an escapement control member included in said spacingcontrol means for causing disengagement of said escapement dog from saidrack, and, i. a connecting member for directly interconnecting saidescapement control member and said pawl-turning member as to be securedto each other.
 3. A mechanism according to claim 2, comprising incombination: j. a first cam included in said operable means and powerdriven from an inoperative position to an operative position to so movesaid support on depression of said key and power driven from saidoperative position to said inoperative position on release of said keyto cause said support to be restored, and k. a second cam included insaid spacing control means and power operated cyclically to actuate saidpawl-turning and escapement control members in such a manner that saidescapement dog when disengaged in this way performs a retrograde strokeand reengages said rack after said retrograde stroke independently ofsaid first cam.
 4. A half-spaced carriage return mechanism for atypewriter having a letter space carriage advance mechanism whichincludes an escapement dog engageable with a toothed spacing memberconnected to the carriage for holding the carriage against the action ofthe carriage advance biasing means, and means for disengaging the dogfor allowing the carriage to advance under bias and for reengaging saiddog with said spacing member for stopping said carriage after it hasadvanced one character space, comprising: a pawl, normally uncoupledfrom said spacing member, a depressible half-space carriage return key,means operated by the depression of said key for displacing said pawlfor engaging said pawl with said spacing member to return said carriageby one-half character space, said engaging means holding said pawl inits displaced position as long as said key is depressed, means coupledto and operable substantially simultaneously with said escapement dogdisengaging means for disengaging said pawl, only when said pawl is inits displaced position, from said spacing member substantiallysimultaneously with the disengaging of said dog, and means forrecoupling said pawl with said spacing member to stop said spacingmember after it has advanced under the influence of said biasing means adistance of one character space from said half character space returnedposition.